1. Field of the Invention
This invention concerns hydride coordination complexes of transition metals of Groups IVB and VB, containing tertiary phosphines.
2. Description of the Prior Art
Heretofore, successful attempts to isolate hydride complexes of Group IVB metals, Nb and Ta, have been made by invoking the added stabilizing ability of special .pi.-bonded ligands such as .pi.-cyclopentadienyl. The very stability of the metal-cyclopentadienyl bond, however, prevents such groups from labile inter-conversion with hydride or other ligands. Thus, as shown by Marvich and Brintzinger, J. Am. Chem. Soc., 93, 2046 (1971) for Ti and by Barefield, Parshall and Tebbe, ibid., 92, 5234 (1970) for Nb and Ta, the cyclopentadienyl ligands cannot be reversibly replaced by multiple hydride ligands or other coordinating groups.
The novel hydrides of this invention contain ligands that are sufficiently stable for isolation and yet sufficiently labile to afford ready replacement by reacting species during use, say, in promoting hydrogen transfer reactions. The novel hydrides are soluble in organic media and thus are particularly desirable to facilitate homogeneous hydrogen transfer reactions.